The mandate of "Healthy People 2000 is a 20% reduction in the number of people, aged 65 years and older, requiring assistance for personal care activities by the year 2000. This goal can only be fully realized by identifying he etiologies and consequences as well as the determinants of the course and incipient signs of a major cause of impaired function in the elderly: Alzheimer's disease (AD) and related dementias, particularly stroke. During the previous funding period, we developed a population-based registry for dementia and used information from this resource to investigate the epidemiology of AD and other forms of dementia (stroke and Parkinson's disease) in the ethnically diverse community of Washington Heights-Inwood in New York City. We have completed estimates of the prevalence and incidence of dementia, primarily AD and the dementias associated with stroke and Parkinson's disease (PD). We used the case-reporting system or registry: 1) to develop methods to assess dementia that consider the various cultural and educational backgrounds of our community; 2) to identify clinical predictors for various types (SRD) and PD in a series of case-control studies using recently diagnosed cases and controls from this community. In this renewal application it will become apparent that we have strengthened and streamlined our methods for case-ascertainment and follow up by merging the diagnostic screen and neuropsychological assessment into a single step at the same interview using computer technology. We have incorporated functional assessment by field and laboratory methods and biologic markers (brain imaging and bioassays) into this renewal. We intend to investigate specific hypotheses developed through the relationship of the North Manhattan Aging Project and the Clinical Core in the previous funding period. First: environmental, dietary and genetic factors associated with incident AD, stroke and SRD will be explored; in second functional and biological correlates and consequences of cognitive decline and its relationship to incipient dementia will be investigated; and third: the late consequences and course of AD will be explored. Finally, using our community base we shall confront issues we consider fundamental to the etiology, course and late consequences of AD and related disorders.